Mouse model of Sanfilippo syndrome type B produced by targeted disruption of the gene encoding alpha-N-acetylglucosaminidase

The Sanfilippo syndrome type B is an autosomal recessive disorder caused by mutation in the gene (NAGLU) encoding alpha-N-acetylglucosaminidase, a lysosomal enzyme required for the stepwise degradation of heparan sulfate. The most serious manifestations are profound mental retardation, intractable behavior problems, and death in the second decade. To generate a model for studies of pathophysiology and of potential therapy, we disrupted exon 6 of Naglu, the homologous mouse gene. Naglu-/- mice were healthy and fertile while young and could survive for 8-12 mo. They were totally deficient in alpha-N-acetylglucosaminidase and had massive accumulation of heparan sulfate in liver and kidney as well as secondary changes in activity of several other lysosomal enzymes in liver and brain and elevation of gangliosides G(M2) and G(M3) in brain. Vacuolation was seen in many cells, including macrophages, epithelial cells, and neurons, and became more prominent with age. Although most vacuoles contained finely granular material characteristic of glycosaminoglycan accumulation, large pleiomorphic inclusions were seen in some neurons and pericytes in the brain. Abnormal hypoactive behavior was manifested by 4.5-mo-old Naglu-/- mice in an open field test; the hyperactivity that is characteristic of affected children was not observed even in younger mice. In a Pavlovian fear conditioning test, the 4.5-mo-old mutant mice showed normal response to context, indicating intact hippocampal-dependent learning, but reduced response to a conditioning tone, perhaps attributable to hearing impairment. The phenotype of the alpha-N-acetylglucosaminidase-deficient mice is sufficiently similar to that of patients with the Sanfilippo syndrome type B to make these mice a good model for study of pathophysiology and for development of therapy.

Is postoperative haematoma an avoidable complication of intracranial surgery?

Postoperative intracranial haematoma is a serious complication of intracranial surgery with a mortality rate of around 30%. There have been reports implicating abrupt rises of blood pressure during the last stages or immediately after the procedure, in the production of the clot. This prospective study examined this hypothesis. Over the last 7 years, 526 consecutive patients underwent craniotomy under a strict anaesthesiological protocol based on deep opioid analgesia which virtually eliminated any acute elevations of the arterial pressure during and immediately after craniotomy. Emergence from anaesthesia was delayed for an average of 1 1/2-2 h following the procedure. Postoperative CT was obtained in every patient. There have been no cases of postoperative clot formation in this series of patients. The results of the study suggest that postoperative haematoma is probably an avoidable complication of intracranial surgery.

Thecoperitoneal shunt for post-traumatic syringomyelia

A case of post-traumatic syringomyelia developing two years after spinal cord injury is presented. The patient was treated with the placement of a thecoperitoneal shunt incorporating a low pressure valve. Response was excellent with restoration of neurological function and almost complete collapse of the cavity at one year follow up. The rationale of this form of treatment is discussed in the light of recent evidence concerning the pathogenesis of the condition.

Thecoperitoneal shunt for syringomyelia: report of three cases

During 8 months, three consecutive cases of syringomyelia were treated by the placement of thecoperitoneal shunts. In the first two patients, the cord cavitation was idiopathic in one and thought to be related to spinal trauma in the other. In the third case, there was associated anomaly of the craniocervical junction of the Chiari I type. Surgery was followed by clinical improvement in all patients. Postoperative magnetic resonance images showed definite diminution of the syringomyelic cavity. The results of treatment seem to support the use of the technique as a primary treatment of syringomyelia associated with progressive myelopathy.